A clinical-stage biotechnology company specializing in targeted RNA medicines for rare genetic neuromuscular disorders, ARTHEx Biotech, has successfully upsized its Series B financing round to a total of $87 million. The additional funding was led by new investor Bpifrance, with all existing shareholders, including AdBio Partners, CDTI Innovación, Columbus Venture Partners, European Innovation Council (EIC), Hadean Ventures, Invivo Partners, and Sound Bioventures, also renewing their participation. The capital raised will primarily be used to advance the company's lead program, ATX-01, a therapy for Myotonic Dystrophy Type 1 (DM1). This includes funding for the ongoing Phase I/IIa ArthemiR™ study and preparing for an open-label extension to support a future registrational study.

ATX-01 is an anti-miR oligonucleotide that targets and inhibits microRNA23b (miR-23b), a molecule that naturally represses the expression of the MBNL protein. In patients with DM1, the MBNL protein is dysfunctional due to both its reduced expression and its sequestration by toxic DMPK mRNA. By inhibiting miR-23b, ATX-01 works through a dual mechanism to increase MBNL protein production and reduce the formation of toxic mRNA, thereby correcting splicing abnormalities and restoring function. This approach has shown promising in vitro and in vivo results, demonstrating significant molecular and functional improvements in animal models. In addition to advancing ATX-01, the company plans to use the new funding to expand its pipeline of targeted RNA medicines to address other areas of high unmet need in muscular, CNS, and cardiac conditions.